From the end of FR381, which is about four tenths of a mile north of Clohesy Lake, follow the designated trail south that skirts the lake and private property and gains nearly 200 vertical feet. At the high point on this trail above the lake, another trail splits off for Missouri Mtn. Continue past that and lose elevation back down to near creek level as you continue south about another .7 mile. Keep an eye on the west slopes above the Lake Fork Creek. There are three prominent avalanche gullies. The first is the widest. The next two have intermittent streams. At the second chute, cross the Lake Fork and head up the gully. These coordinates may help: N 38° 56' 09.89" W 106° 24' 21.82"
Once your heading up this fairly narrow chute, the best way to avoid the numerous willows is to hike on the south side, just inside the edge of the forest. We found numerous game trails to assist. After about 1,000 feet of gain, you'll break out of the trees and find yourself just north of elevation marker 12,264. Continue up the beautiful valley of lush tundra with a rivulet running through it and scattered boulders. Continue hiking WSW in ever increasing boulders, aiming for the saddle between UN13,513 and newly ranked 13,472/13,486. From below, this may begin to look like madness as you begin to see the rugged section of cliffs and rocks below that saddle. When you arrive at the foot of the cliffs below the saddle, with some careful route finding, you can find a way up utilizing various ledges that should not exceed Class 3. For us, the route never got any worse than a hard Class 2+, but be prepared for Class 3 scrambling.
At the base of the cliffs, turn left and look for an upward sloping ledge that you can follow for a ways before it terminates and then follow a system of additional ledges that generally head toward the summit of UN13,513 as you work your way up and through the cliffs. After a while, the ledge system plays out and you'll have a choice. Either head directly for the saddle or contour over to a shallow gully (left). We chose the gully partly because the mountain goats seemed to prefer that route. (It should be noted, it's not always wise to follow mountain goat tracks - they climb things we wouldn't do without a rope and protection!) Once in this gully, it became just steep hiking which eventually brought us out on a ridge about 50 yards east of the summit. Stumble on up to the top over plenty of rocks. If you will examine a Google Earth image of this side of the peak closely, you can see more than one gully that tends south toward the east ridge of the peak. For your descent, return by the same route or....
Bonus Points: You may want to include the newly ranked summit to the north of 13,486 ft. We are now including these two summits as a sequenced route. Previously, this summit was considered to be about 10 feet short of qualifying as a ranked 13er, because the saddle elevation is interpolated and not actually measured. According to recent Lidar technology/measurements, this summit qualifies as a ranked 13er now with an elevation of 13,486 ft. It may be possible to reach it by following the connecting ridge from UN13,513 north, but we thought it looked rather daunting and difficult, so we descended off UN13,513 as we had come up, back to the bottom of the cliffs.